This invention relates generally to a navigation or route guidance system and, more particularly, to a vehicle location display for a route guidance system.
Navigation systems generally provide a recommended route from a starting point to a desired destination. Generally, the starting point and desired destination are selected from a large database of roads stored in a mass media storage, such as a CD ROM or hard drive, which includes the roads in the area to be travelled by the user. The navigation system can be located in a personal computer or it can be installed in a vehicle. If the navigation system is installed in a vehicle, the starting point is typically the current position of the vehicle, which can be input to the navigation system by an associated position determining system that usually includes a GPS (Global Positioning System) receiver.
The navigation system determines a route from the starting point to the destination utilizing an algorithm well-known to those in the art and currently in use in many navigation systems. Usually there are many potential routes between the selected starting point and the desired destination. Typical navigation systems select a recommended route based upon certain "cost" values associated with each segment of road in the road database. These cost values include the length of the road segment and the estimated time of travel through the road segment. The navigation system selects the potential route with the lowest total cost to be the recommended route. Depending upon the predetermined algorithm of the navigation system, the navigation system will recommend the route with the shortest total length, the lowest total time, or some weighted average of length and time.
The recommended route is then displayed to the user as a map showing the starting point, desired destination and highlighting the recommended route. Preferably, if the navigation system is installed in a vehicle, the navigation system displays the current location of the vehicle and provides turn-by-turn instructions to the driver, guiding the driver to the selected destination.
The typical navigation system provides the current vehicle location to the user by displaying either a textual guidance mode screen having a set of instructions and the current location or a guidance mode map showing the starting point, desired destination, current location and highlighting the recommended route. When a user has not determined a route, the typical navigation system displays a map showing the current vehicle location and all of the surrounding streets. Such a system is described in U.S. Pat. No. 6,049,755 filed Jul. 13, 1998, which claims benefit of provisional application Ser. No. 60/084,292, filed May 5, 1998. The disclosures of U.S. Pat. No. 6,049,755 and 60/084,292 referenced above are hereby incorporated by reference in full.
The typical navigation system also permits a user to adjust the scale of a displayed map. Frequently a user desires to "zoom out" by increasing the map scale to enable the user to see a larger area of the database. One disadvantage of current map zoom functions is that when a user zooms out it can be difficult, because of the complexity of a larger scale map, to see the current vehicle location on the large scale map. Also, in a current navigation system when a smaller scale map is displayed the user is provided with the name of streets on the map, this information can not be provided on the larger scale display.
The typical navigation system also permits a user to pan the map to areas other than the current location. One disadvantage when panning a large scale map is that the user is not provided with a street name of a panned street.
Thus, it is desirable to provide a vehicle location display for a navigation system that permits a user to alter the scale of a displayed map to a large scale while still providing the user with information concerning the current vehicle location. In addition, it is desirable to provide information to a user regarding a panned street when the scale of a displayed map is large.